Ultrasonic prism



Jan. 20, 1948. w. P. MASON 2,434,667

ULTRASONIC PRISM Filed June 5, 1943 2 Sheets-Sheet 1 2 I TO IZTKC.

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INVENTOR W P MASON ATTORNEY Jan. 20, 1948. w. P. MASON ULTRASONIC PRISM Filed June 5, 1943 2 Sheets-Sheet 2 q 3 3 Na \v Qv V B B QM mm 9M A T TORNEI' 11v VE/V TOR n. I? MASON Patented Jam- 20, 1948 UNITED STATE S PATENT OFFICE to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 5, 1943, Serial No. 489,761

Claims. (Cl. 177386) This invention relates to locating devices and particularly to that class of devices by which ultrasonic vibrations set up by propellers of ships are located in direction.

The invention makes use of certain principles of prismatic determination which are completely disclosed in my copending applications, one entitled "Pipe antennas and prisms, Serial No. 381,236, filed March 1, 1941, Patent No. 2,408,435,. and another entitled Prismatic and high power compressional wave radiators and receivers, Serial No. 431,558, filed February 19, 1942, Patent No. 2,404,391. In some aspects the present invention is an improvement on the device disclosed in my copending application entitled "Submarine detecting device, Serial No. 477,916, filed March 4, 1943.

The object of the invention is to provide a prismatic device having a range of 360 degrees or a full sweep in all directions about a given point. Heretofore and particularly by means of the submarine detecting device disclosed in my lastmentioned application the azimuth angle of a source of disturbance could be determined, but in that case the determination was made by calculation after making at least two angular determinations by at least two separate but similar prisms. The object of the present invention is to provide a prismatic device which will cover the whole range of 360 degrees and give a single response constituting a direct indication of the azimuth angle.

In accordance with the present invention a plurality of prisms each having a difierent' range are physically located with respect to each other to cover 360 degrees and placed in an electrical netformation each would only be called upon to operate over a range of plus or minus 60 degrees and hence the accuracy of the device as a whole would be improved. By the same token a device having four legs regularly spaced would require each leg to respond over a range of plus or minus 45 degrees with a consequent still further improvement in accuracy. In general, the larger number of legs employed resulting in the lesser range covered by each leg leads to greater accuracy. It will be recognized that this subdivision may be carried out until the prisms each with an extremely narrow range are arranged in a circle. Ultimately in this process the prisms will lose their identity as prisms and the discrimination will occur wholly in the associated network.

As a preferred embodiment of the invention a device having four legs is disclosed herein by way of example.

A feature of the invention is a prismatic re- I sponsive device for covering a complete azimuthal work whereby each is rendered active over its particular range.

The simplest embodiment of the invention comprises a pair of prisms each capable of a range of 180 degrees and arranged in a filter network whereby as one prism reaches its limit of response the other begins to function.

It will e appreciated however that these prismatic devices have response characteristics whereby the greatest accuracy centers about the line normal to the longitudinal axis thereof so that if the range of the device is limited to a smaller range than its complete capability its accuracy is improved. v'I'hus the simple Jprism is capable of a range of plus or minus 90 degrees and so two placed parallel to each other and in a position that might be termed back to back are capable of covering 360 degrees. However, if three such prisms are placed in an equilateral range consisting of a plurality of prisms each having a range consisting of a corresponding fractional part of said complete range.

Another feature of the invention is a device comprising a plurality of prisms in combination with an electrical network which will automatically admit to each prism only currents within its range.

A further feature of the invention is an elec- -trical network which will automatically transfer admission of different frequency currents into a plurality of difierent prisms in ranges of the highest accuracy of the same prisms.

Another feature of the invention is an electromechanical transducer comprising a plurality of prisms physically arranged with the lines normal to their longitudinal axes radiating at equal angles from a common point and anetwork associated therewith for controlling said prisms each within that portion of its range measured by the angles formed between said radii.

Other features will appear hereinafter.

The drawings consist of two sheets having seven figures as follows:

Fig. 1 is a geometrical diagram showing how two prisms placed back to back will cover a range of 360 degrees;

Fig. 2 is a similar geometrical diagram showing how three prisms located along the legs of an equilateral triangle will cover a range of 360 degrees;

' gle frequency determination of an incoming sig- 3 Fig. 4 is a theoretical plan view of a.360-degree tions as shown in Fig. 6, the filter sections being prism showing the plan of four crystal arrays of the confluent band-pass type as shown by Fig.

with frequency ranges indicated by way of ex- '1. The band width of the filters is designed so ample; that at the edge of the frequency ranges of in- Fig.5 is a graphical diagram showing the over- 5 terest, i. e., to 13.3 kilocycles for example, the lapping characteristics of the four prisms; beam patterns of each side have been related Fig. 6 is a schematic circuit diagram showing from 45 degrees to +45 degrees. In the bandhow the electrical connections to the four prisms pass filter of Fig. '7 this gives a uniform Iremay be made; and quency distribution. These values require that Fig. '7 is aschematic circuitdiagram indicating 10 the band-pass filters of each section have the the type of filter used between the various .cryscut-off frequencies as follows: tals in each prism. I 2 1 b k t Fig. 1 shows two prisms and p aced ac o m cut-oflfreback. The line normal to the face of the prism I mama enemies is the line ca and this prism is capable of working over a range plus and minus 90 degrees from such 9 c4 and 13 a line. In the same manner the prism 2 is capable 12 85nd 1s 0a of working over a range plus and minus 90 de- 13333 2%;

grees from the line cb normal to its face. In this manner two prisms may be made to cover the entire azimuthal range The frequency ranges of With such values the overlapping characteristics the two prisms I and 2 will then be different but Wm be as depicted m 5 so that the effective range of each prism will be as heretofore given. preferably substantially continuous so that a sin In F1 g 6 separate amplifiers 26 to 29 are com nal will give a definite direction or the transmission of a single predetermined frequency will be projected in a definite direction the said amplifiers there is a filter for each section I h which passes the frequency range of interest 4 5:51 2 53 1 3211: th o il g lf ri t hg lzg z fgn gfil and has a 3-dec1bel discrimination at the band dge. These are all placed in parallel and direct lateral triangle. In this case the prism; is cae pable of covering a range of plus and minus 90 the applied energy to the proper amplifier In degrees from the line de normal to its face but will need to cover only a range of plus and minus 60 degrees or the range within the angle 'gdf. The overlapping portions between 1 and i and between nd k will be covered b he a 'acent prisms 4 and 5, respectively. In :his c se the 22 to 25 and thence passed through one or the three prisms will have frequency ranges each g of amplifiers 26 to 29 to one or the gg different but all arranged to provide a continuous o P- 9 Sections .Q of e switch to pattern Each prism will be fed-through a band its-alternate position will reverse the direction f the amplifiers and direct the parallel connecpass filter which will pass only those frequencies 0 useful in the selected partof the total'mnge tion from the filters to a receiver 32 instead of thereof, 5 -the oscillator 31.

Fig v shows a Similar arrangement wherein In the lowest frequency range if the oscillator four risms are em 10 ed so that only the'range puts out frequencies m the range 10 to plus minus 2 from the line normal kilocycles the angular direction of the beam will tween the main connection to this device and switch 30 whereby the device may be used either as a projector or a receiver. In the position shown, energy from a source of oscillations 3| is fed in parallel to each of the band-'pass filters to t fa of the prism will he used be between -45 degrees and +45 degrees, with By way of example the four prisms will be arzero angle measured from ma to the low ranged to work over the following ranges; frequency surface.- As the frequency approaches the energywill beimpressed, on the second section. This is adjusted, however, to have" its angle at +45 degrees at the same frequency as the lowest frequency radiator so that the angle will vary continuously as the frequency is increased. From 13.3 kilocycles to 17.7 kilocycles y the angle will vary from +45 degrees to +135 dewhereby any particular frequency between 10 grees, then the third surface will start radiating, and 31.4 kilocycles may be projected in a given and so on. In this way the an can be Varied direction of the entire azimuthal range or the continuously from 0 degrees to 360 degrees by Prism j Range direction of any incoming signal having a transvarying the frequency of the oscillator 3| from mission including this whole range may be ac- 10 to 31.4 kilocycles. curately determined. The device shown in its circuit arrangement The general construction is shown in Fig. 4 in Fig. 6, shows the first section consisting of Where a square framework is provided on which six crystals 33 to 38 having filters 39 to 43 and a nected to each line of filters and crystals. Be-

Fig. 6 the device is shown as controlled by a 50 thedividing'freque'ncy of 13.3 kilocycles some of v the crystals and their backing resonators are terminating network 44 in line therewith. The

mounted. The lowest frequency range has six band-pass filter 22 feeding this section is decrystal blocks Hi to l5 and their backing resosigned to pass a band of frequencies 10 to 13.3 nators 16 to 2!, respectively. It is arranged in kilocycles before it overlaps the characteristics this way so that the separation between blocks 7 of the next filter as shown in Fig. 5. The other shall be in the order of .4 of a wavelength sections are shown in accordance with the pre- The next range has eight blocks, the third has vious description and in accordance with the ten blocks and the highest frequency range has figures and values given by way of example. fourteen blocks. Such a device may be useful for scanning all Each row of crystals is placed across filter secangles at the same time. If a source of resistthe greatest.

ance noise is placed at the input, that is used as the oscillator 3|, then the different frequencies Then by operating lar direction of interest. More power can be I sent out in that direction since the entire power carrying capacity of one amplifier can be directed to this direction.

The resolving power or the device will be least for the lowest frequencies but the range will be which the figures and values heretofore given apply about 1000 watts of acoustic energy can be radiated. This amounts to 56 watts for a degree angular range which is equal to present standards. Hence. even on a scanning system which scans the whole horizon at one pulse the distance and resolution obtainable are as good as are obtained by present standards. When a single range is radiated considerably more power and distance can be covered than is 'now possible.

What is claimed is:

1. An electromechanical transducer compris-- For the size now in use and for their ranges measured by the angles formed belongitudinal axes radiate from a common point and an electrical network associated therewith for controlling said crystal arrays within that portion of their ranges measured by the angles formed between said radii. I

3. An electromechanical transducer comprising-a plurality of electromechanical translating prisms of the compressional-wave, frequencydirection'al type each having a potential range of degrees and responsive to different and overlapping bands of frequencies, said prisms being arranged with their longitudinal axes forming an equilateral polygon and an electrical network associated therowith for controlling said prisms each within a portion of its range measured by radii from the center of said polygon to the extremitie of the chord formed by the longitudinal axis thereof.

4. An electromechanical transducer comprising four electromechanical translating prisms of the compressional-wave, frequency-directional type each having a potential range of 180 degrees and responsive to different and overlapping bands of frequencies, said prisms being arranged with .their longitudinal axes forming a square and an electrical network associated therewith for controlling said prisms each within a portion of its range measured by angles of plus and minus 45 degrees from a line normal to its said longitudinal axis.

5. -An electromechanical transducer comprising a plurality of crystal arrays each prismatically responsive to a different bandvof frequencies, said bands comprising contiguous portions of a single band, each said crystal array having a given range and the sum 0! said ranges of said plurality of crystal arrays comprising a complete azimuthal range of 360 degrees, said crystal arrays being physically arranged with respect to each other so that lines normal to their longitudinal axes radiate froma common point andan electrical network associated therewith for controlling said crystal arrays within that portion Of said complete azimuth range measured by the angles formed between said radii.

WARREN P. MASON.

REFERENCES CITED The'following references are of record in the file of this patent:

v UNITED STATES r'a'r' srrrs Number Name Date 2,169,304 Tournier ,Aug. 15, 1939 467,102 Huber'et al. Jan. 12, 1892 1,348,826 Fessenden Aug. 3; 1920 1,149,122 Fuller Aug. 3, 1915 1,384,014 Fessenden July 5, 1921 

